Mission Success - Indian PSLV delivers seven Satellites to Orbit

February 25, 2013

*File Image* - Photo: Indian Space Research Organisation

An Indian Polar Satellite Launch Vehicle successfully delivered seven payloads to orbit on Monday, among those were the French-Indian SARAL and the two Canadian NEOSSat and Sapphire. The launcher blasted off from the Satish Dhawan Space Center on India’s East Coast at 12:31 UTC, beginning a 22-minute mission to reach Sun-Synchronous Orbit.

The 59-hour PSLV Countdown Sequence started early on Saturday. During the Countdown, the second and fourth stage were loaded with storable propellants and the reaction control systems of the first and upper stage were fueled as well. The Mobile Service Tower was retracted to its launch position 160 meters from the launch pad on Sunday to get ready for final countdown operations and Liftoff.

The PSLV launcher blasted off on time, at 12:31 UTC – 18:01 local time, the opening of a 20-minute launch window. As clocks hit zero, the large Core Stage of the vehicle ignited and the 44.5-meter rocket lifted off with a total liftoff thrust of 496,000 Kilograms being provided by the solid fueled PS1 stage.

This flight used the Core Alone Version of the PSLV without the six Solid Rocket Boosters on the first stage. The PS1 stage of the launcher has a liftoff mass of 168,200kg being 2.8 meters in diameter and 20.34 meters long. It consists of five segments that are loaded with solid HTPB-based propellant. Vehicle control is provided via Secondary Injection Thrust Vector Control for pitch & yaw and two thrusters for roll.

As the vehicle started its ascent, it pitched over to depart India’s East Coast. To avoid the Island of Sri Lanka, the PSLV Launcher flew a Dogleg Trajectory which is a guided, powered turn during the ascent phase of a Rocket Flight. The maneuver comes at the cost of ascent capability, but range safety requirements dictate that the vehicle can not fly over inhabited areas. When the launcher was clear of the island, it started flying south-west to reach its desired orbital inclination.

1 minute and 53 seconds into the flight, at an altitude of 51 Kilometers, the first stage separated from the liquid-fueled second stage that ignited just 0.3 seconds after separation. The second stage of the PSLV launcher is powered by a 799-Kilonewton Vikas engine that consumes Unsymmetrical Dimethylhydrazine and Nitrogen Tetroxide. The second stage is 12.8 meters long and has a liftoff mass of 46,000kg. It powered the vehicle for 2 minutes and 32 seconds.

At T+2:58 as the vehicle passed 116 Kilometers in altitude, the protective payload fairing was separated as the launcher had left the dense atmosphere and aeroheating was no longer of concern. PSLV’s fairing is 3.2 meters in diameter and 8.3 meters long.

Third stage ignition occurred at T+4:25 and the stage burned for 112 seconds, providing at thrust of 244 Kilonewtons. The third stage has a reduced diameter of 2.02 meter. It is 3.54 meters long and has a launch mass of 7,800kg. Vehicle control was provided by the fourth stage attitude control system. After the burn was complete, the launch vehicle began a short coast phase during which it held onto the third stage. Third stage separation occurred at T+8:40 at an altitude of 582 Kilometers while the vehicle was moving at 5,300m/s. Once the third stage was away, the vehicle began its fourth stage burn which started at T+8:51. The Upper Stage fired for 8 minute and 22 seconds to boost the stack into orbit. PSLV’s Upper Stage is powered by two L-2-5 engines providing a total thrust of 14.6 Kilonewtons. The engines use Monomethylhydrazine and Mixed Oxides of Nitrogen as propellants. The stage is 2.6 meters long, 2.02m in diameter and has a liftoff mass of 2,520kg.

Fourth Stage shutdown occurred at T+17:21 as the vehicle achieved it desired orbit. Shutdown came at an altitude of 789 Kilometers and a velocity of 7,453m/s. The vehicle reached a 790.5 by 780.6-Kilometer orbit at an inclination of 98.5 degrees.

After shutdown, the Reaction Control System of the fourth stage re-oriented the vehicle for SARAL Spacecraft Separation just 37 seconds after shutdown. SARAL was released as planned, being sent on its way to start a 7-year mission to monitor the Earth. With the primary payload released successfully, the PSLV jettisoned the payload adapter to expose the two larger secondary satellite, NEOSSat and Sapphire which subsequently were released at T+18:57 and T+19:22, respectively. The other four small satellites, BRITE, Uni-BRITE, AAUSAT-3 and STRaND-1 were separated between T+20 and T+22 minutes, completing the primary mission of the launch vehicle. To finish its mission, the fourth stage completed a Collision Avoidance Maneuver and underwent passivation.

Photo: Indian Space Research Organisation

This flight marked the 23rd PSLV flight since its inauguration in 1993 and the first Indian space mission of 2013. Two more PSLV flights are planed for this year. One of those will launch the Indian MangalYaan Mars Orbiter. India’s Geosynchronous Satellite Launch Vehicle will also return to flight in the first half of 2013.

Payload Information

SARAL

SARAL or Satellite with ARgos and ALtiKa is an Earth Sensing Spacecraft that was developed by the Indian Space Research Organisation and the French Space Agency CNES. the satellite will also be operated by those two agencies. The satellite is part of the Global Monitoring for Environment and Security (GMES) initiative of the European Commission and the European Space Agency. It will fill a gap between Europe's Envisat Program and Sentinel 3 mission, being similar to the NASA/NOAA/EUMETSAT Jason-2 mission. SARAL features four payloads, the AltiKa altimeter, DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), a Laser Reflector Array and the ARGOS-3 system (Advanced Research and Global Observation Satellite).

SARAL will support environmental monitoring, oceanography and altimetry. SARAL will observe Ocean mesa-scale variability which is a high-energy process "with wave lengths within a 50km to 500km range, and with periods of a few days to one year," a CNES document said. Measuring meso-scale dynamics is essential for understanding ocean dynamics, circulation and climatic effects. SARAL will also measure the main continental water level and sea level variations. It will also observe the polar oceans, study wave fields and sea ice, and examine marine biogeochemistry. AltiKa is a Ka-Band altimeter that will provide data with very high spatial and vertical resolution to enable better observations of ice, coastal areas, continental water bodies and wave height. Similar systems are also used on Envisat and Jason-2 to ensure data continuity into the future. AltiKa is the first altimeter to operate at such high frequencies which holds two advantages. Previous altimeters rely on radar systems which a susceptible to atmospheric properties that can influence measurements by effecting the speed of radar signals so that satellites needed to carry additional equipment to correct measurements. The second advantage is a much higher accuracy.

Photo: Indian Space Research Organisation

AltiKa will provide ocean surface topography measurements with an accuracy of 8 millimeters at a spatial resolution of 2 Kilometers. AltiKa can also function as radiometer to provide atmospheric water content.

DORIS - Doppler Orbitography and Radiopositioning Integrated by Satellite - is a French system used for precise Satellite Orbit Determination and Positioning. The system features ground beacons and antennas on orbiting spacecraft that receive signals coming from the ground and make use of the frequency shift of the signal caused by the satellite's movement. The Doppler Effect is used to precisely determine the satellite's orbit along with other positional data. A total of 50 beacons are installed all over the world to allow continuous orbital tracking. The ground system infrastructure of the system is fairly simple as it only requires beacon transmitters that do not need to receive any data as the DORIS payload on the satellite is responsible for orbit determination and data storage/relay. DORIS enables orbit determination with an accuracy of two centimeters which is required to Earth/Ocean topography measurements.

The Laser Retroreflector Array instrument is used for calibration of other Precise Orbit Determination instruments by shooting a laser from the ground with its beam being reflected by the LRA mirrors.

Photo: Indian Space Research Organisation

Photo: CNES

ARGOS-3 is part of the ARGOS System which features a worldwide network of transmitters and ground stations to acquire, relay, downlink and process environmental data in real time or near real time. ARGO transmitters can be installed on mobile platforms such as sea vessels or fixed platforms, buoys and maritime animals like sea turtles.

The project has been established in 1978 in an agreement between CNES, NOAA and NASA and since then, the number of transmitters has been steadily increasing. The ground transmitters can be small sensors just measuring a few environmental properties, but many remote weather stations that acquire large data sets are also part of the system.

The ground platforms record environmental data and periodically transmit it via UHF frequency which is picked up by orbiting spacecraft. The data sets are then relayed via X-Band to one of 40 ground stations, usually in real time, so that the data can be transmitted to an ARGOS center in the US or France for processing and distribution.

The SARAL Satellite Bus was provided by the Indian Space Research Organisation. The vehicle is based on the IMS-2 Small Satellite Bus weighing about 409 Kilograms at launch. The satellite bus is 0.98 by 0.98 y 2.6 meters in size. The satellite features two 1.2 by 1.4-meter solar arrays that deploy once in orbit for a total power generation of 570 watts. Telemetry downlink is accomplished via S-Band that provides a 64kbit/s link for telemetry downlink and 4kbit/s uplink speed. The satellite has an expected lifetime of 7 years.

Secondary Payloads

In addition to SARAL, PSLV C20 will carry 6 small satellites to orbit that are released after SARAL has been sent on its way.

NEOSSat (Near Earth Object Surveillance Satellite)NEOSSat was developed by the Canadian Space Agency and Defence Research and Development Canada. The satellite is a small space telescope dedicated to monitoring Near Earth Asteroids and Space Debris. The mission will split its time 50/50 between the search for asteroids and the monitoring of satellites and space debris. The satellite uses a 15-centimeter aperture Maksutov telescope. It is a three-axis stabilized platform with a liftoff weight of 74 Kilograms.

"The hundreds of images that NEOSSat will generate per day will be downloaded and analyzed by the University of Calgary's NEOSSat science operations centre. Through NEOSSat, Canada will contribute to the international effort to catalogue the near-Earth population of asteroids producing information that will be crucial to targeting new destinations for future space exploration missions," a Canadian Space Agency Document said.SapphireSapphire is a 148-Kilogram satellite that will be operated by the Canadian Department of National Defence to track spacecraft at orbital altitudes of 6,000 to 40,000 Kilometers. The Satellite was built by Surrey Satellite Technology and is based on the firm's SSTL-150 satellite platform. The main payload of the vehicle is a space-based electro-optical sensor featuring a 15-centimeter telescope with a field of view of 1.4 degrees. Data collected by the satellite will be shared with the US Space Surveillance Network.

Image: Canadian Space Agency

NEOSSat

Image: University of Vienna

BRITE design

BRITE (BRIght-star Target Explorer) & UniBRITEThese satellites are a small 14-Kilogram Spacecraft developed at the Technical University of Graz and the University of Vienna, Austria as well as the University of Toronto, Canada.

They feature a star sensor that will photometrically measure the low-level oscillations and temperature variations of bright stars. The difference between the two spacecraft is an optical filter that allows UniBRITE to observe the blue region of the spectrum. The satellites are 20 by 20 by 20 centimeters in size and feature solar arrays on their exterior panels. The spacecraft are three-axis stabilized and have a power consumption of up to 10 watts. They feature VHF, UHF and S-Band Data Relay system that achieve a maximum data rate of 256kbit/s. The satellites generate a daily data volume of about 2MB.

AAUSAT 31-Unit Cubesat from the Aalborg university, Denmark. The 3-Kilogram satellite features a dual band AIS receiver for a technical demonstration of receiving AIS signals from ships in the arctic region. A Phoenix GPS receiver provided by the German Aerospace Center is also part of the satellite.

STRaND-1STRaND-1 is a technical demonstration satellite that was built by Surrey Satellite Technology and is part of the company's Training Research and Nanosatellite Program. It is a 3-Unit Cubesat weighing about 6 Kilograms. The vehicle is built around the Google Nexus Smartphone and is dedicated to testing off-the-shelf components to advance space technology.

"During the first phase of the mission, STRaND-1 will use a number a number of experimental Apps to collect data while a new high-speed linux-based cubesat computer developed by SSC takes care of the satellite. During phase two, the STRaND team hope to switch the satellite's in-orbit operations to the smartphone, thereby testing the capabilities of a number of standard smartphone components for a space environment," Surrey Satellite Technology say on their website.

India ready for first PSLV Launch of 2013

February 23, 2013

Photo: Indian Space Research Organisation

An Indian Polar Satellite Launch Vehicle is being prepared for launch on Monday from the Satish Dhawan Space Center to deliver the SARAL Environmental Satellite and six secondary payloads to Sun-Synchronous Orbit. Liftoff is planned to occur on Monday, February 25 at 12:26 UTC, the opening of a 20-minute launch window. The mission was originally planned to occur in 2012, but was hit by a number of delays, pushing it into 2013. The launcher and payloads were integrated at the Space Center to get ready for the mission that is preceded by a 59-hour countdown sequence that begins on Saturday. Official approval to go ahead with the launch was given this week. Nominal Countdown operations include the Propellant Loading of the second and fourth stage of the PSLV Launcher. Stages one and three are both solid-fueled. Also during the countdown, extensive checks of the rocket and the spacecraft are conducted as well as battery. In addition to that, India’s Ground Network of Tracking Stations is being configured for the flight.

A detailed PSLV Launch Vehicle Overview is available here. The C20 PSLV Launcher is flying in the Core Alone Configuration.

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